Position Determination System (PDS) devices such as devices that determine position using the satellites of the US Global Positioning System typically include a GPS antenna, a GPS receiver, a GPS processor, and a data storage device. Signals from the GPS are received by the GPS antenna, processed by the GPS receiver and position is determined by the GPS processor. However, typically, the computation of position using signals from the GPS system gives position in an Earth Centered Earth Fixed (ECEF) format that includes ECEF coordinates.
The indication of position in ECEF coordinates is not particularly useful for most applications. Maritime users, campers, hikers, and other users in remote locations typically want to know their position in terms of latitude and longitude. Users in urban areas typically want to know their position as a street address. Alternatively, users desire to know position relative to major landmarks, or relative to nearby cross streets.
The conversion of position into other coordinate systems requires that conversion algorithms and/or extensive databases be stored in the PDS device. This requires a high capacity memory storage device. High capacity memory storage devices sufficient to store the large databases and conversion algorithms are quite expensive. Also, usage is complicated by the fact that new streets, addresses, and landmarks are constantly being added and existing streets, addresses and landmarks are frequently changed. Therefore, the databases used must be frequently updated. The updating process is expensive and time consuming. In addition, the microprocessor must be quick and powerful to search the database and convert the determined position into the desired reference system in a timely manner. This adds even more expense to the PDS device.
As usage of the GPS has grown in popularity, there has been a need for economical devices that allow for the determination of the position of the user. However, GPS processors are expensive as are memory storage devices. In addition, maintenance of devices for determining position that indicated position in different formats is expensive and difficult due to the need to frequently update the stored databases.
Recently, message transmission devices that allow persons to easily send messages have become popular. These message transmission devices include computers, handheld computers, digital telephones and digital pagers. The communication systems that are used by recent message transmission devices include, for example, the internet, cellular telephone networks, paging networks, wireless data transmission networks, telephone transmission lines and cable systems.
Typically, message transmission devices include a keypad that allows a user to compose a message. Many message transmission devices use commonly available software programs such as Eudora, Netscape Navigator, etc. that generate messages conforming to a standard format. A typical message contains a body and one or more headers. The headers indicate the final destination to which the message is to be sent and the identity of the sender.
One commonly used format for messages is the Standard Mail Transmission Protocol (SMTP) format. The SMTP format is used for almost all internet message transmissions. Due to the popularity and widespread use of the SMTP format for internet transmission, the SMTP format is also being increasingly used for non-internet communications.
Servers are used to route messages to their final destination. Servers that route messages that conform to the SMTP format (SMTP servers) route messages based on information contained in a header. Typically, such servers only route messages, they do not alter the text in the body of the message. Instead, headers are often added, deleted, or otherwise altered by the server to route the message to the desired final destination.
Because of the relatively high cost of adding position determination capabilities to message transmission devices, these devices do not typically include position determination capabilities. However, it is often desirable for a user of a message transmission device to know his position. In addition, the user's position is often needed to properly route a message. This is particularly true when a user of a message transmission device needs to contact or locate the nearest facility of a service provider such as, for example, the nearest gas station, the nearest bank branch, etc.
What is needed is a way for a user of a message transmission device to determine position and to indicate position in a message. In addition, a way to determine position is needed that couples position to a user in a desired format, without the need to store and update extensive databases on the device being used. Still another need exists for a device that meets the above-listed needs and that is inexpensive. Yet another need exists for a method and apparatus for routing of messages according to the position of the sender. The present invention provides a solution to the above needs.